It is commonplace to utilize a portable electric space heater as a sole or supplemental source for heating rooms of personal dwellings, baths, garages, work areas, or the like as the occasion to use such chilled area arises. Conventionally there is some thermostatic control for energizing the heater only up to a specified temperature, and then for deenergizing the heater. Some heaters have only radiant or convective heat distribution, while others use a fan for circulating the ambient air through the heater for more rapid and even heat distribution to the surroundings.
Thus far, commerically available portable electric space heaters have lacked accurate means of regulating the heat output to the end that the heater either was energized or was deenergized. This operation is less than satisfying since without any heat being emitted from the deenergized heater, cold sensations or drafts frequently cause discomfort; whereas continuous operation of the heater at the high level output might direct excessive heat for uncomfortable or even unsafe conditions.
Further commerical considerations are the degree of portability and attractiveness of the heater which might readily blend in with the background decor. The heater also must have safety standards to minimize the possibility of electrically shocking an individual because of exposed heating elements or of burning an individual because of excessively high operating case temperatures.
Various patents which illustrate heaters of the general type discussed herein, as well as which show various control circuits which heretofore have been employed are illustrated in U.S. Pat. No. 1,107,319 - F. Kuhn; U.S. Pat. No. 1,982,139 A. J. Kercher; U.S. Pat. No. 2,647,198 - M. E. Lautner; U.S. Pat. No. 2,697,164 - A. S. Knapp et al; U.S. Pat. No. 2,722,594 - J. J. Kueser; U.S. Pat. No. 3,019,324 - J. P. Sohn; and U.S. Pat. No. 3,114,812 - R. N. Levinn.